It is often desirable to be able to prevent climbing access to ladders. This is especially true where ladders present an attractive nuisance to children, and where ladders provide ready access to vehicles, buildings, or towers. A child can be injured while climbing any ladder. There is a need for some type of ladder guard for preventing unauthorized use of ladders. The prior art includes several ladder guards.
In U.S. Pat. No. 2,880,829 (1959) Watkins discloses a shield used to cover the horizontal cross bars of a triangular tower. The triangular shield is self supported by a hook on its upper end that slips over a horizontal cross bar, thus suspending the device over a number of cross bars to effectively prevent ascension of the tower. Watkins' shield is only suited to triangular towers.
In U.S. Pat. No. 3,225,863 Ludlow (1965) discloses a hinged attachment to be affixed to a ladder to prevent the unauthorized use of the ladder. This device consists of a smooth panel covering several horizontal cross bars of a ladder which is side hinged to swing out allowing use of the ladder. Ludlow's construction is much more elaborate than the present invention and must be permanently installed.
In U.S. Pat. No. 3,311,195 Singer (1967) discloses a ladder guard designed primarily for use with above ground swimming pools. This is a safety device consisting of a flat panel covering several ladder steps to prevent small children from climbing up the ladder into the pool area. The Singer ladder lock employs hooks in a manner similar to the present invention, but does not allow for locking, and thus may be easily removed by children and others. The Singer device also is not adaptable for different sized ladders.
In U.S. Pat. No. 3,372,772 Singer (1968) discloses a device similar to his first but with the additional feature of a self-latching support mechanism which latches via a spring loaded tongue to the underside of the horizontal cross bars of the ladder. Singer's device is not adjustable and may be removed by anyone by merely pushing the spring-loaded tongues.
In U.S. Pat. No. 3,968,857 (1976) Bryan discloses a safety shield and support mechanism that can be attached to any type of ladder with horizontal cross members. The device consists of a support mechanism attached to the cross bars of the ladder. The support mechanism is bolted to the cross bars and thus is designed to be permanently affixed. A flat shield is locked onto the support mechanism. The flat shield covers several cross bars of the ladder to prevent ascension. Bryan's shield is very elaborate and must be permanently bolted to the ladder.
In U.S. Pat. No. 4,126,206 (1978) Becnel discloses a ladder guard consisting of two flat plates which are hinged together at the mid-point. The upper plate has a hook which slips over a horizontal cross bar of the ladder. The hinge allows the plates to be pulled outward from the ladder and to slip the lower plate between two cross bars and behind the ladder. This allows access to a locking device from the front of the ladder. Becnel's guard must be custom manufactured to fit a particular ladder.
In U.S. Pat. No. 4,181,195 (1980) Clarke discloses a ladder guard for use with recreational vehicles. The device consists of a flat panel that slips over an upper cross bar of the ladder and is suspended over the lower cross bars. The invention discloses a keyed locking mechanism that secures the ladder guard to a lower cross bar on the ladder. Clarke's guard is not adjustable and will not fit right for ladders with different rung spacing. The Clarke ladder lock also is not adaptable to different sized ladders, and few stores can afford the space to effectively display such a huge device.
In U.S. Pat. No. 4,450,937 (1984) Broughton discloses a step ladder with a flat panel on one side. This device can be attached, with the flat panel facing outward, to an existing ladder such as those found on recreational vehicles. The flat panel prevents the ascension of the ladder in order to prevent the theft of items stored on top of the recreational vehicle. The ladder can also be removed to provide a separate step ladder. Broughton's step ladder addresses a different need than the present invention.
In U.S. Pat. No. 4,579,197 (1986) Spurling discloses a safety device for use with above ground swimming pools. The flat shield is gravity supported at the base of the ladder. It rests up against the ladder and is secured by a locking bar that slips through two holes in the sides of the shield and behind the ladder. Spurling's device will not accommodate wide or narrow ladders. It also must rest on the ground and thus will not work on mobile ladders.
In summary the present invention solves two problems. First it is no longer necessary to custom fit a ladder guard to a particular ladder. Second it is no longer necessary to permanently mount a ladder guard to a particular ladder. The present invention is both portable and universally adaptable to all ladders.